Plugged EGR tube?
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From: Michigan
Plugged EGR tube?
Just wondering if anyone has ever experienced having a plugged egr tube? I had a code for egr insufficient flow last year and went throught the whole throttle body cleaning writeup. Which was very useful, thanks f50online! Some nasty stuff builds up on these 4/6's. Codes gone and runs good. Just thinking though that there could also be build up in the egr tube that runs from the egr valve to the manifold. Does anybody know what the orifice inside the tube looks like or have a pic of? What is the best way to go about cleaning out the tube? Thanks!
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Joined: Oct 2005
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From: MI
Just wondering if anyone has ever experienced having a plugged egr tube? I had a code for egr insufficient flow last year and went throught the whole throttle body cleaning writeup. Which was very useful, thanks f50online! Some nasty stuff builds up on these 4/6's. Codes gone and runs good. Just thinking though that there could also be build up in the egr tube that runs from the egr valve to the manifold. Does anybody know what the orifice inside the tube looks like or have a pic of? What is the best way to go about cleaning out the tube? Thanks!
Nah, the EGR Orifice tube requires no maintenance and is ironwork only. However, in order for the device to function correctly it must be gas tight both at the exhaust and the inlet ends.
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From: Easton, Pa.
The orfice seldom blocks but anything is possible.
You can tell if it is open by removing the rubber connector tubes to the DPFE, starting the motor and feeling the pulses at each tube.
The upper tube above the orfice must feel the exhaust pulsing or the orfice would be blocked.
Even use a vacuum gauge on this port while blocking the lower one and raised engine idle should show some 'positive' pressure because the EGR is closed.
This is how the system tests for closed integrity and uses the 402 code to report it if it fails. So a blocked orfice could be reported by this code.
The DPFE must see (no differencial) pressure to pass the 402 test.
Cleaning is often simple if it is just carbon by using carb cleaner into the upper test port and let is work awhile, then start to motor for a test feel as mentioned above..
You can tell if it is open by removing the rubber connector tubes to the DPFE, starting the motor and feeling the pulses at each tube.
The upper tube above the orfice must feel the exhaust pulsing or the orfice would be blocked.
Even use a vacuum gauge on this port while blocking the lower one and raised engine idle should show some 'positive' pressure because the EGR is closed.
This is how the system tests for closed integrity and uses the 402 code to report it if it fails. So a blocked orfice could be reported by this code.
The DPFE must see (no differencial) pressure to pass the 402 test.
Cleaning is often simple if it is just carbon by using carb cleaner into the upper test port and let is work awhile, then start to motor for a test feel as mentioned above..
Last edited by Bluegrass; Mar 23, 2009 at 03:44 AM.
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From: Michigan
Thanks for the replies. I wasn't sure if it could get blocked up or not. Sounds like a simple test to see. With all the carbon in these engines you never know. After seeing what was in my TB I guess I'm kinda freaked out now.
Last edited by 98f150guy; Mar 23, 2009 at 01:06 PM.
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From: Easton, Pa.
I see many have an issue with EGR blockage.
On my 02, in 115,000 miles only 1 DPFE has been replaced at about 35,000 and the EGR port has been clean, so far.
Much of the time it depends on how the truck is driven.
Short runs of less than 10 miles does not heat the motor enough to keep it clean.
At cold starting, it is 'cold rich' in fuel in the exhaust. This carbon is driven passed the orfice to colder surfaces of the tube, EGR valve and intake manifold where it condenses and accumulates to blockage.
At start up certain EGR tests are done that help cause the carbon to build, as an unintended consequence.
In addition, moisture is in the exhaust and collects internally to form a paste that eventually hardens in place.
The moisture combined with gases corrode and block the DPFE into fault.
This is one reason the motor has to be well heated each time it is used.
On my 02, in 115,000 miles only 1 DPFE has been replaced at about 35,000 and the EGR port has been clean, so far.
Much of the time it depends on how the truck is driven.
Short runs of less than 10 miles does not heat the motor enough to keep it clean.
At cold starting, it is 'cold rich' in fuel in the exhaust. This carbon is driven passed the orfice to colder surfaces of the tube, EGR valve and intake manifold where it condenses and accumulates to blockage.
At start up certain EGR tests are done that help cause the carbon to build, as an unintended consequence.
In addition, moisture is in the exhaust and collects internally to form a paste that eventually hardens in place.
The moisture combined with gases corrode and block the DPFE into fault.
This is one reason the motor has to be well heated each time it is used.
